A Bragg silicon lattice comparator

The basic principle and the results of the feasibility study of a Bragg lattice parameter comparator, developed within the framework of the Standards, Measurements, and Testing European Project silicon for mass unit and standard (SIMUS) are described. It combines a Bragg lattice comparator (Wart-Hauser-mann design) and an X-ray angle interferometer to determine the angular position of diffraction peaks. Comparisons between Si crystals with a relative uncertainty of 1E-8 are expected.